Nerve cell structures in circumscribed regions of the brain are pathologically, e.g. excessively synchronously, active in patients with neurological diseases such as tinnitus, depression, obsessive compulsive disorders, ADHS or schizophrenia. In this case, a large number of neurons synchronously form action potentials; the participating neurons fire excessively synchronously. In a healthy person, in contrast, the neurons fire with a different quality, i.e. in an uncorrelated manner, in these brain sectors.
Acoustic coordinated reset (CR) stimulation was developed for the treatment of chronic subjective tinnitus; it directly counteracts pathologically synchronous neural activity (P. A. Tass, I. Adamchic, H.-J. Freund, T. von Stackelberg, C. Hauptmann: Counteracting tinnitus by acoustic coordinated reset neuromodulation. Restorative Neurology and Neuroscience 30, 137-159 (2012); I. Adamchic, T. Toth, C. Hauptmann, P. A. Tass: Reversing pathologically increased EEG power by acoustic CR neuromodulation. Human Brain Mapping (in press)) and can also normalize the pathologically modified interactions (so-called effective connectivity) between different brain areas (A. N. Silchenko, I. Adamchic, C. Hauptmann, P. A. Tass: Impact of acoustic coordinated reset neuromodulation on effective connectivity in a neural network of phantom sound. Neuroimage 77, 133-147 (2013)). The acoustic CR stimulation is characterized by therapeutic effectiveness and safety (P. A. Tass, I. Adamchic, H.-J. Freund, T. von Stackelberg, C. Hauptmann: Counteracting tinnitus by acoustic coordinated reset neuromodulation. Restorative Neurology and Neuroscience 30, 137-159 (2012)).
It is of key importance for the effectiveness of the acoustic CR stimulation that the different stimulation sites actually lie in the neural population to be stimulated. There is no imaging process which could determine the spatial extent of pathological neural synchronization. The CR therapeutic sounds are thus not determined by means of an objective method, but rather by means of an audiometric procedure which is based on psychoacoustics and is thus deficient to a different degree depending on the patient. The dominant tinnitus frequency is first determined audiometrically in the audiometric adaptation of the CR sounds. This typically does not work with patients having noise tinnitus, but rather only with patients having tonal tinnitus. The pitches of the CR therapeutic sounds are rigidly predefined (P. A. Tass, I. Adamchic, H.-J. Freund, T. von Stackelberg, C. Hauptmann: Counteracting tinnitus by acoustic coordinated reset neuromodulation. Restorative Neurology and Neuroscience 30, 137-159 (2012)). In a second step, the loudness of the therapeutic sounds is balanced with rigidly predefined pitches (which are e.g. in the range from 77% up to 140% of the dominant pitch of the tinnitus) (i.e. the loudness of the CR therapeutic sounds is set to the same subjective loudness where possible).
Approximately 25% of patients having tonal tinnitus do not respond to this therapy (P. A. Tass, I. Adamchic, H.-J. Freund, T. von Stackelberg, C. Hauptmann: Counteracting tinnitus by acoustic coordinated reset neuromodulation. Restorative Neurology and Neuroscience 30, 137-159 (2012)). This approximately corresponds to the percentage of patients having tonal tinnitus who cannot make any pitch balance between their tinnitus and a computer comparison sound. In addition the CR treatment in its current form (i.e. with the above-described audiometric adaptation of the CR sounds) is only suitable with limitations for patients having noise tinnitus within a narrow band and is not suitable for patients having noise tinnitus within a broad band. On the one hand, an (audiometrically determinable) dominant tinnitus frequency is lacking and, on the other hand, the rigidly predefined arrangement of the pitches of the CR therapeutic sounds (e.g. in the range from 77% up to 140% of the dominant pitch of the tinnitus) is typically not suitable since the pathologically synchronous focus underlying the noise tinnitus e.g. has a different extent in the central audiometric system than in the case of tonal tinnitus.
An analog situation results in the case of the treatment of other brain diseases such as ADHS, depression, obsessive compulsive disorders or schizophrenia with acoustic CR stimulation. The choice of the suitable CR therapeutic sounds up to now has only been able to be carried out audiometrically or using trial and error. Time-consuming trial and error does not guarantee the ideal effectiveness of the non-invasive CR therapy since, on the one hand, not all possible stimulation sites in the brain are systematically developed and tested and, on the other hand, the patients are stressed by long examinations so that the cooperation of the patients naturally suffers and the results of the test become worse.